About the only thing, to my knowledge, that's really different or unusual about Metanx is the methylated version of folic acid, which is easier for the body to use chemically and which is otherwise hard to obtain.

Otherwise, the rest of the ingredients are quite easy to obtain over the counter, and relatively cheaply. but, if one has good insurance coverage and a low co-pay for prescriptions, it might make sense to take the Rx root in getting these vitamins.

Daisymay gave you an excellent thread to read about this--MrsD is one of our really expert vitamin/supplement/med people, and she backs up her posts with good references.